ABSTRACT
The most conspicuous feature is the appearance of morphological resonances whose origins are drastically different in semi-conductor and metal nanoparticles: they are associated with the quantum mechanical effect in the former, and essentially due to the classical dielectric confinement effect in the metal case. The weaker role of quantum confinement in metal nanoparticles is a consequence of their large electron density as compared to the semiconductor case. In optical experiments, one is generally dealing with a composite material formed by an ensemble of nanoparticles dispersed in a dielectric matrix. In the case of metal nanoparticles dispersed in a dielectric matrix, a similar approach can be introduced, taking into account electron localization at a nanoscale. For nanoparticles, the electron energy can also be damped to the surrounding solvent or matrix, either directly or via the metal lattice, possibly modifying the observed relaxation. The chapter discusses time-resolved optical investigation of the non-equilibrium electron relaxation in large metal nanoparticles.
